Field of the Invention
The present invention relates to a polarizing plate and a liquid crystal display device.
Description of the Related Art
A liquid crystal display device uses liquid crystal switching to visualize the polarization state. Based on the display principle, the liquid crystal display device uses a polarizing plate in which a transparent protective film is bonded to each of both surfaces of a polarizer with an adhesive layer interposed therebetween. Iodine polarizers made of stretched polyvinyl alcohol to which iodine is adsorbed have high transmittance and high degree of polarization. Therefore, they are most popular polarizers widely used as the polarizer. A transparent protective film having a high water vapor permeability such as a triacetylcellulose film is used.
Image display devices such as a liquid crystal display device to which the polarizing plate is applied are used under various environments. Therefore, the polarizing plate is desired to have durabilities such as heat resistance under a high temperature environment and humidity resistance under a high humidity environment. However, the triacetylcellulose film usually used as the transparent protective film has a largely changed retardation under a high humidity environment, which disadvantageously causes display unevenness on a panel. On the other hand, there has been proposed a technique of reducing a water vapor permeability using a transparent protective film containing a (meth)acrylic resin, to suppress display unevenness (see Patent Document 1).